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formula for alloy?

Is any one familiar with a math formula that will give an accurate and repeatable percentage for alloy content? I'm only looking for the tin percentage in batch sizes and solder types that will vary. Assuming that WW's have a .5% tin content, and my target is 1%. Today I may be looking at 10lbs of WW's and have 60/40 solder, wile tomorrow it may be 50lbs of WW's and 90/10 solder.

Thanks in advance

Nora

If you don't have the time to do it right, when are you going to find the time to fix it?

Add one ounce (or pound)of tin per every 100 ounces (or pounds) of lead or alloy as the case may be. If your alloy already has 1/2% tin, add only 1/2 % more. Solders are by weight. To get one ounce of tin from 50/50 solder add 2 ozs of solder. In this case you would add 1 oz if you only wanted 1/2% more tin. Same kind of calculation with 63/37 - 63 in to 100 (inverse) = approx 1 2/3 oz solder yeilds 1 oz tin. If you want 1/2 % tin multiply this by .5 (1.67X.5).

Last edited by leftiye; 05-25-2009 at 04:02 PM.

We need somebody/something to keep the government (cops and bureaucrats too) HONEST (by non government oversight).

Every "freedom" (latitude) given to government is a loophole in the rule of law. Every loophole in the rule of law is another hole in our freedom. When they even obey the law that is. Too often government seems to feel itself above the law.

You are perfectly correct in that the hardness of Tin is about BHN 7. The
problem is that in a lead tin alloy at the molecular level the organization of
the atoms leads to an overall greater bond strength (simplification) and a
greater BHN. Using Lead BHN ~5 and Tin BHN ~7 and looking at just the initial
hardness of pure substances gives no indication of final product hardness. The
results must be all empirically determined. Different configurations in the
microstructure are possible for different concentrations in the alloy and
different cooling rates - also affecting BHN. For the alloy this is not in a
linear relationship but the easiest quick and dirty method is to give the tin
a BHN of 30 and not 7 in calculations. Low value BHN alloys are the hardest to
calculate and stock alloy recipes are the best to use - see Lyman website
perhaps. Now if other trace elements that cause hardening are present such as
Zinc, Silver or Arsenic, it becomes quite difficult to predict the eventual
hardness of the alloy with any finesse.

I'm not sure which excel version of alloy03.xls spreadsheet you have...? ( Yes
more than one with the same name - sorry)

Attached is perhaps a different form of the Excel Alloy spreadsheet for you to
use.
Most of the spreadsheet cells are locked - unlock with the password "alloy".
Fairly pedantic I know so to unlock use: > Tools > Protection > Unprotect Sheet > alloy

I would stress that the best worksheet to refer to is the one labeled as "BHN
Chart". The two moving points, one red - additions as weights and one green -
additions as percentages, are generated from the tin and antimony percentages
from the previous pages. This chart is an adaptation (slightly simplified
curves around the 23 - 24 BHN equipotential lines) from a 1950's publication
and is much more dependable than the BHN calculations on the excel sheet. Try
various combinations and you will see that some give quite different results
than expected. The tabulated hardness of the pure tin and pure antimony are of
course incorrect ( should be lower as mentioned above) but are used this way
in an attempt to calculate simply the hardening effects seen in the final
alloy. Obviously the BHN chart page has limited functionality in the low < 16
BHN area - where most of my shooting interests lie.

The chart is the best graphical BHN estimation chart I know of for "Pure"
Lead/ Tin/ Antimony alloys.

On the "Print page", (no laughing please) the data (for example set in
original attachment):